Harry Eakins
A simple robot with 2 motors and 2 encoders. Motor speed is set to 40 and PID controllers are use to attain that speed
Dependencies: PinDetect mbed mRotaryEncoder PID
Revision 0:e019949c4c69, committed 2011-09-20
- Comitter:
- harryeakins
- Date:
- Tue Sep 20 12:55:47 2011 +0000
- Commit message:
- Initial version
Changed in this revision
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/HBridgeMotor.lib Tue Sep 20 12:55:47 2011 +0000 @@ -0,0 +1,1 @@ +http://mbed.org/users/harryeakins/code/HBridgeMotor/#a3bcb7eab9d9
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/PID.lib Tue Sep 20 12:55:47 2011 +0000 @@ -0,0 +1,1 @@ +http://mbed.org/users/aberk/code/PID/#6e12a3e5af19
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/PinDetect.lib Tue Sep 20 12:55:47 2011 +0000 @@ -0,0 +1,1 @@ +http://mbed.org/users/AjK/code/PinDetect/#cb3afc45028b
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/mRotaryEncoder.lib Tue Sep 20 12:55:47 2011 +0000 @@ -0,0 +1,1 @@ +http://mbed.org/users/charly/code/mRotaryEncoder/#75ddffaf3721
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp Tue Sep 20 12:55:47 2011 +0000
@@ -0,0 +1,68 @@
+#include "mbed.h"
+
+#include "mRotaryEncoder.h"
+#include "HBridgeMotor.h"
+#include "PID.h"
+
+// PID constants
+#define RATE 0.2
+#define Kc 1.5 // Proportional
+#define Ti 1.0 // Integral
+#define Td 0.0 // Derivative
+
+DigitalOut led1(LED1);
+
+// Two PID Controllers
+PID leftPID(Kc, Ti, Td, RATE);
+PID rightPID(Kc, Ti, Td, RATE);
+
+// Two de-bounced encoders
+mRotaryEncoder left_enc(p19, p20, p29);
+mRotaryEncoder right_enc(p26, p27, p28);
+
+// Two motor/h-bridge objects
+HBridgeMotor left_motor(p25, p24);
+HBridgeMotor right_motor(p21, p22);
+
+void initializePidControllers(void) {
+ leftPID.setInputLimits(-300, 300);
+ leftPID.setOutputLimits(-1.0, 1.0);
+ leftPID.setMode(AUTO_MODE);
+
+ rightPID.setInputLimits(-300, 300);
+ rightPID.setOutputLimits(-1.0, 1.0);
+ rightPID.setMode(AUTO_MODE);
+}
+
+int main() {
+ int left_pulses = 0, right_pulses = 0;
+
+ initializePidControllers();
+
+ // 40 encoder ticks per second target speed
+ leftPID.setSetPoint(40.0);
+ rightPID.setSetPoint(40.0);
+
+ while (true) {
+ // Get velocities
+ float left_velocity = float(left_enc.Get() - left_pulses)/RATE;
+ float right_velocity = float(right_enc.Get() - right_pulses)/RATE;
+
+ // Pass the PID Controller the latest velocity value
+ leftPID.setProcessValue(left_velocity);
+ rightPID.setProcessValue(right_velocity);
+
+ // Query the PID Controllers for the desired power outputs
+ // and set the motors to those powers
+ left_motor.set(leftPID.compute());
+ right_motor.set(rightPID.compute());
+
+ // Save the number of encoder ticks for velocity calculation in the next loop
+ left_pulses = left_enc.Get();
+ right_pulses = right_enc.Get();
+
+ // Toggle the LED and wait
+ led1 = 1 - led1;
+ wait(RATE);
+ }
+}
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/mbed.bld Tue Sep 20 12:55:47 2011 +0000 @@ -0,0 +1,1 @@ +http://mbed.org/users/mbed_official/code/mbed/builds/63bcd7ba4912